Process for purifying iron.



PATENTED FEB. 18, 1908.

E. VON MALTITZ.

PROCESS FOR PURIEYING IRON.

APPLICATION FILED APR. 30, 1906.

2 SHEETS-SHEET 1 40mwA 4 Maw PATENTED FEB. 18, 1908.

E. VON MALTITZ. PROCESS FOR PU RIFYING IRON.

APPLIOATIOH FILED AYE. 30, 1906.

2 SHEETS-SHEET 2.

nveiia'f:

EDMUND VON MALTITZ, OF CHICAGO, ILLINOIS.

PROCESS FOR PURIFYING IRON.

Specification of Letters Patent.

Patented Feb. 18, 1908- Lpplieation filed April 30- 1906 Serial No.314.367-

T till whomit may concern:

these medium grad; ores has heretofore been Be itknown that I, EDMI'NI)von MALTITZ, g convertible into steel only by the open hearth a citizenof Germany, residing at Chicago, in the county of ook and State ofIllinois, have process. The open hearth processes are, however,comparatively slow and much more invented a certain new and usefulProcess expensive.

for Purifying: li'on, of which the following is a specification. f

This invention relates to an improved process for purifying ironpreparatory. to making steel or for use. otherwise where it.is desirableto have the metal low in mpurities and particularly low in carbon.silicon, phosphorus and sulfur. I

AS is understood by those skilled in the art in the making of steel inaccordance with the Bessemer and analogous processes, melted pig iron issubj cted to an oxidizing trea .ment in a sunablc furnace for the.purpose or oxidizing and eliminating the impurities contained in theiron until the percentages remaining are below that which is permissiblein the steel and until the carbon is either practically all removedready for rc-carburization or eliminated down to that. carbon contentwhich the. steel is to have.

Numerous processes have been devised for making steel after this generalplan. but each more or less limited in its applications. For example. incarrying out the Bessemer process, phosphorus and sulfur cannot besufficiently eliminated and it is therefore necessary to use aparticular kind of iron derived from a high grade ore which is low inphosphorus, and because of its limited quantity, com arativelyexpensive.

T 1e basic Bessemer or Thomas process deends to a lnrgc extent upon theheat evolved liythe oxidationof phosphorus. It has therefore been foundnecessary to use pig iron with not less than one per cent. phosphorus incarrying out this process. Between the grades of iron suitable for usewith the Bessemer process and those suitable for use with the 'lhmnasprocess, there is a wide range of irons too low in phosphorus for theone process and too high for the other, and therefore unusable foreither. As a matter of fact the chief bulk of the iron orcs derived fromthe Lake Superior districts, which constitute the chief source of suiply for the iron industries of the country today, are of those grailcsmediurn in phos )horus and unsuitable for the Beas er o: homas)roccsscs, while the low phos Joni .=o callerl Bessemer ores") are.rapidly becoming exhausted. The iron from i l i it is the object of thepresent invention to provide a process which is effective in eliminatinthe impurities usually contained in iron; which is not limited in itsapplicationto certain kinds of iron only but 1s suitable for use in'purifying iron derived from a wide range of ores; to provide a processwhich minimizes the defects likely to be found in steel, such as are dueto occluded gases, or to the presence of an excess of phosphorus; toprovide a process which is simple, rapid and inexpensive, and does notentail the use of special doctoring of the metal; to provide a processwhich may be carried out by the use of simple and thoroughly practicalapparatus; and in general to provide an improved process of thecharacter referred to.

The invention will be most readily understood by a description of themethod, as performed with the aid of a vessel and suitable associatedapparatus particularly designed for carrying out this method, but it isto be understood that the method is in no Fig. 2 is an.

Referring to the drawings, 1, l, designate a pair of base standardssuitably spaced apart and at their upper ends suitably shaped to formconcave parti-circular tracks 3, upon which is mounted a cradle frame 4.Anti-friction rolls 5 are journaled in the standards l,thc peripheriesof which support the track surfaces of the cradle 4. The two sidemembers 6 of the cradle are at each end brought together at the top toform trunnion hearing; 7, within which are journaled the trunnions 8 ofan oval vessel 2. Upon one c'nd of the vessel, adjacent to its trunnionand concentrically with the axis of the latter, is mounted a large gearQwhich meshes with a spur-gcar 10 carried by a shaft 11 and having atits opposite end a worm-gear 12. The

ii ll worm-gear is in turn engaged by e worm-. 2 same, together withenough burnt lime to shaft 13 carrying a bevel-gear l4 and actuinsurethe presence for reaction purposes of ated by a hovel-pinion 15 mountedupon the l a strongly basic slag. The charge of iron shaft lo (11' anelectric motor 17. The entire l may be varied at will, so lon as it doesnot cradle frame so as to movebodily with the latter.

In Order to impart a tilting or oscillator) movement to the cradle andthe vessel supm ported therein. a parti-circular rack 18 is providedrigidh united with the two side members of the cradle frame by means ofcross bars It! and arranged parallel or concentric with the trucksurfaces of the cradle;

to a worm-gear 20 mounted upon a shaft 21 journaled in suitable bearingsupon the standard fl'tllllt l.

are hollow to provide inlet and outlet pass sages 27 and 28,respectively, communicatpipe 29, communicating with a suitah source ofpressure, as for example a blower 30, is' arranged to extend into theinlet trun nion of the vessel and terminates in a nozzle 31 which isdesirably directed so as to anse the blast to switch horizontallythrougn the vessel across the surface of the batch of material therein,and impinging against that wall 40 of the vessel which is rotatingupwardly and where the metal is exposed from beneath the slag, asindicated in dotted lines at 32, Fig. 3, and as will hereinafter morefully appear. A suitable tunnel or discharge pi 33 is detachablyconnected wit-h the opposite end of the vessel, whereby the outflow.blast is deflected and directed u wardly. It is to be understood alsothat the blast pipe 29 will be eitherdetachably or flexibly connectedwith the vessel so as to not interfere with the oscillatory movements ofthe latter.

In operation the vessel 2 will be rotated upon its longitudinal axiswhile maintained in substantially horizontal position during.

the rinci al art of the time in carrying out the trt htm ient of themetal, and will be tilted when it is desired to dischargo the batchafter treatment. The vessel may also be oscillated or tilted as toaltornlwly 6 raise one end and then the other'durin'g the carrying outof the process, if it be so deired.

In carrying out the process in conjunction with the apparatus described,after the vets lel has been thoroughly heated, a suitableuchzrgoofmeltedironilehargedintoth this rack being provided with teethadapted The shaft 21 extends obliquely downward and carries at its lower3 mg with the interior of the vessel. A blast silica and generatesconsiderable heat.

train of gear moclmnismds mounted on the overflow from the vessel. Theapparatus is 79 now set in motion to revolve the vessel; for a vessellarge enough to treat fifteen tons of metal ion batch at say from ten toforty revolutions per minute. As soon as the vessel beins to revolve, ablast of air is turned on of ow pressure, throu h the twyer, which blastis preferably though not necessarily so directed as to impinge againstthe surface of the metal along that wall of the vessel which is rotatingupwardly, or. in other words, 30 where the rotary movement of the vesselexposes the surface of the metal proper from ieneath the slag. The blasttraverses the length of the vessel and )asses out through the dischargefunnel. he element most promptly attacked by the oxygen of the blown inair is the silicon, which oxidizes to Thecarbon of the iron will beoxidized to carbonic oxid, under the action of heat, and the carbonicoxid will in turn be burned into carbonic dioxid inside of the vessel.This combustion thus taking place in the vessel, on account of itsenormous heat evolvin capacitp, will raise the temperature of the 5 metarapidly to a. point where general oxidation of all of the oxidizableelements is prometed and ensues. This high temperature will, of course,result in forming a liberal quantity of slag at an early stage of theproc- 00 ess, which slag will in turn become at once active ineliminating the phosphorus which combines with the basic slag. in otherwords, practically the entire heat-evolving capacity of the silicon,carbon, manganese and phosphorus is utilized for raising the temperatureof the metal and formin slag as rapidly as ossible, with correspon inglyra id cherni reactions;

he air, it will be noted, is not passed through the metal, as in theBessemer process, thus avoiding to the cutest extent the charging of themetal wit nitrogen and hydrogen, due to decomposition of moisture in theair, (objectionable because tending to increase the occluded gases inthe metal) but nevertheless all parts of the metal are soon subjected tothe oxidizing efiect of the air bocause the rotation of the vesselcontinually exposes fresh surfaces of the metal from, beneath the slag.The present process, therefore, is comparatively rapid, and thus avoidsthe comparatively great length'of time required to treat in accordancewith those methods, where the oxidation is effected while the metal iscomparatively quiescent in the vessel, (the Robert and Tropenas proc-'esses are examples) and it also avoids the objectionable features of theBessemer rocolc, or Bessemer-Thomas process, no

llrlll.

. svaaao a The process having been inaugurated, as described, themechanical rotation and blast may be continued until the impurities areeliminated to the desired extent. ()r, without interrupting'therotation. the blast may be either restricted or entirely interrupted ata stage when the slag contains enough iron oxids to act as a purifyingagent which will supply the necessary oxygen to continue the eliminationof the impurities by oxidation. By so doing 1. recover to a greater orless extent the iron in the slag, which would otherwise he lost.containing oxygen in the form of ferrous oxid will also thus be deprivedof this objectionable c pound. wiich is prone to cause blow-l s in thesolidifying steel. I may now either first draw off the slag and thenproceed to recarburize and convert the g batch into steel in the usualmanner wlrile still contained in the vessel. By so doing I am able toutilize the agitating movement of the vessel to insure perfect mixing ofthe metal with the recarburizing and deoxidizing 5 ingredients. ()r lmay tap off the charge of metal before removing the slag and beforerecarlmrizing, or I may first draw off the slag and then the metal.Either of these ways of handlin the metal after it has been purified ispermissible.

It is to be noted that in carrying out my proce s not only does theoxidation take place chiefly at the surface of the metal, bu therevolving movement of the vessel will 3. obviously. under thecentrifugal action of the 5 to which the metal is subjected during thewhole process will facilitate the elimination of occluded gases, just asthe stirring of a:

hatch of metal after it has been poured into the hullcdocs.

.5 As bcreinhefsre intimated, there are a number of factors whichcontribute in the production of an extremely high temperature m thecombustion space within the vessel and above the batch of metal, whichtemperature,

.5 in conjunction with other factors, effects t :e speedy consummationof the treatment. 'l'hc temperature produced is so high that exce it forthe fact that the position of the ves sci is constantly changed it wouldresult in so very rapidly destroying the lining and breaktime toconstantly subject different parts of ing down the vessel. In carryingout the process in a preferred manner, in which the vessel is somanipulated as to constantly turn up fresh surfaces of metal,.and at thesame Furthermore the metal the wall of the vessel to the greatest heat,two distinct and important results follow. Those portions of the vesselwhich for the time being are above the metal, and constitute the roof ofthe combustion chamber, are gradually raised in temperature, but at thesame time these highly heated portions are constantly carried downwardbeneath the melted hatch which is inevitably of somewhat lowertemperature. with the result that the walls of the vessel are maintainedsufficiently below the tern rature obtaining in the combustion c amberto preserve them. or at least very greatly prolong the life of thelining. At the same time the excess of heat imparted to that portion ofthe vessel forming the roof of the combustion chamber is in turnimparted to the molten mass as it descends beneath the same, thuscontributi to the temperature of the latter and hastening the process.-'Another important result of the rotary movement of the vessel is thatit imparts a distinct (lZ'CLlltltlOD to the slag supernatant upon themetal. as well as the circulatory movement to the metal itself. That isto say,the surface friction and molecular adhesion between the wall ofthe vessel and the metal' constantly turns up that sid of the metallying against the u rising side of the vessel, and the continualack-tlow of this uplifted metal at the surface carries with it the undersurface portions of the supernatant slag, so that there is a constantcirculatory movement of the slag, the top layers of which flow towardthe rising side of the vessel and the lower layers of which are carriedaway by the molecular friction and cur-r rent effect of the metal. Thiscontinual circulation of the slag, and continual bringing of freshsurfaces of slag and metal together, obviously contributes greatly tothe desired chemical reactions and insures that all rtions of the metalwill, in a comparative y short time, be brought into intimate relationwith the slag, and this at a time immediately following the oxidizingexposure to the air, at which time, the impurities are brought into acondition in readiness to combine chemically with the basic It is to beparticularly noted that the handling of the metal is such that the massis at no time broken u churned or disturbed to such extent astofacilitate the absorption or occlusion ofgases.

While it will be obvious from the foregoing that the im arting ofmovement to the batch by means 0 a. rotary vessel is most effective, yeta different movement might be imparted thereto which would to aconsiderable extent secure the same results without breaking up ordestroying the solidarity of the mass. Accordingly I have herein claimedthe invention broadly, i. e. as notlimited to a manipuiation in which acontinuous onllow in a given direction is imparted to the material, andilizing reactions of the self-contained conhave also claimed theinvention morev narrowly and as limited in this manner.

While I deem it important to so manipulate the metal that its mass shallremain substuntially unbroken during the treatment.

yet it will be obvious that several distinct advantages incident to theprocess may still be secured when it is so modified as to turn u orotherwise agitate the sunfaco portions of the batch to an extent ordegree which more or less interrupts the continuity of the mass. Forexample, the vessel of the appa- T ratus described herein might be.rotated at such a Speed as t llrodu c this effect. New erthelcss thepurifying treatment would bc I carried out, the maintaining of the wallsof the vessel in the relatively cool condition dcscribed would beeffected and the rapid exposure of all parts of the metal to thepurifymg action of the oxidizing blast and action of the slag would beeffected, but owing to the over-exposure of the metal to the oxidizingblast in the resence of the incident beat ob.- taiuing in t iiecombustion chamber, there would be an unnecessary oxidation and loss ofmetal.

I claim as my invention:

1. An in: rovement in the art of purifying metal whicli consists inconfining a mass of fully fluid metal and a su eruatant quantity of slagformed of added asic material in a substantially unbroken body,imparting n.

tents of the batch.

t. Animpi-ovt-d process of purif ing iron which c nsists in confining amass of fluid metal and a supernatant quantity of basic slag in a. bodyof substantially unbroken solidarity, said slug being ful'icetl by thead'- dition of lmsic material of sufficient quantity to substantiallycover and protect against oxidation the surface of the metal, impartingto one or more of the uprising sides of said mass an upwardly flowingmovement which exposes fresh portions of the metal at the top Q surfacethereof from ben ath the slag without substantially disturbing thesolidarity of the mass and concurrently SlllljECtUlg such i exposed.metal to the action of an oxidizing the metal a movement.WlllUl1-(tUIlSlaHtl}" exposes in limited quantities fresh portionsthereof at the surface fron bencath the slag and withoutdestroymg thesolidarity of the mass, subjecting such exposed surfaces to the actionof an oxidizing gas and effecting the refinementof the batch by thatheat due alone to the oxidizin reactions of the sclfcontained contentsof the batch.

2. An improvement in the art of purifying iron which consists inconfining a massof fully fluid metal and a supernatant quantity of slagformed by the addition of basic material in a substantially unbrokenbody, imparting to the metal a movement which constant-ly exposes freshportions thereof at the surface from beneath the slag and withoutdestroying the solidarity of the mass, and subjecting such exposedsurfaces to the action of an oxidizing gas in a confined combustionspace and effecting the refinement of the batch by that heat due aloneto the oxiblnst in a substantially closed combustion space andcfl'ccting the refinement of the batch by that heat due alone to theoxidizing reactions of the self-contained contents of the batch.

4. An improved process of purifying iron which consists in confining ina substantially closed space a suhstantialiv unbroken mass thereof mfluid state together with a supernatant uantity of basic slag, impartingto the batch a bodily rotary circulatory movemcnt which continuallybrings to the surface and exposes from beneath the slag fresh portionsof the metal and continuously imparts a different circulatory Incrementto the slag, and subjecting such exposed surfaces concurrently tothcsaction of an oxidizing as and iltctiflg the refinement of thebatchiy that heatdue alone to the oxidizing reactions ofthcself-contained contents of the hatch.

An improved process of purifying metal which consists in concurrentlysubjecting the molten metal in a substantially closed vessel toim-chanical agitation. to surface oxidation in the 'ircsencc of anoxidizing gas and suit able slag, and to th heatof combustion thercbygenerated, continuing this treatment until the slag contains substantialquantities of iron oxids. the-n checking the oxidation due to theoxidizing gas by restricting or arresting the sup ,ly of such gas andcon inuing the mechanical agitation of the mass, thereby rcducim theiron oxid of the slag and deoxidizing the batch. EDMIYS l) VUX MALTITZ.'itnesscs: ALBERT H. Gnaves, Emma Rust-z.

